Add new log format that is compatible with Kubernetes

Fluentd configuration uses 'log' for the log message
while containerd uses 'msg'. Since we can't have a single
JSON format for both, add another log format and make
debug log configurable.

PiperOrigin-RevId: 219729658
Change-Id: I2a6afc4034d893ab90bafc63b394c4fb62b2a7a0

pkg/log/BUILD

@@ -8,6 +8,7 @@ go_library(
         "glog.go",
         "glog_unsafe.go",
         "json.go",
+        "json_k8s.go",
         "log.go",
     ],
     importpath = "gvisor.googlesource.com/gvisor/pkg/log",

pkg/log/json_k8s.go

@@ -0,0 +1,47 @@
+// Copyright 2018 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package log
+
+import (
+	"encoding/json"
+	"fmt"
+	"time"
+)
+
+type k8sJSONLog struct {
+	Log   string    `json:"log"`
+	Level Level     `json:"level"`
+	Time  time.Time `json:"time"`
+}
+
+// K8sJSONEmitter logs messages in json format that is compatible with
+// Kubernetes fluent configuration.
+type K8sJSONEmitter struct {
+	Writer
+}
+
+// Emit implements Emitter.Emit.
+func (e K8sJSONEmitter) Emit(level Level, timestamp time.Time, format string, v ...interface{}) {
+	j := k8sJSONLog{
+		Log:   fmt.Sprintf(format, v...),
+		Level: level,
+		Time:  timestamp,
+	}
+	b, err := json.Marshal(j)
+	if err != nil {
+		panic(err)
+	}
+	e.Writer.Write(b)
+}

runsc/boot/compat.go

@@ -66,7 +66,7 @@ func newCompatEmitter(logFD int) (*compatEmitter, error) {
 
 	if logFD > 0 {
 		f := os.NewFile(uintptr(logFD), "user log file")
-		target := log.MultiEmitter{c.sink, log.GoogleEmitter{&log.Writer{Next: f}}}
+		target := log.MultiEmitter{c.sink, log.K8sJSONEmitter{log.Writer{Next: f}}}
 		c.sink = &log.BasicLogger{Level: log.Info, Emitter: target}
 	}
 	return c, nil

runsc/boot/config.go

@@ -157,12 +157,15 @@ type Config struct {
 	// LogFilename is the filename to log to, if not empty.
 	LogFilename string
 
-	// LogFormat is the log format, "text" or "json".
+	// LogFormat is the log format.
 	LogFormat string
 
 	// DebugLog is the path to log debug information to, if not empty.
 	DebugLog string
 
+	// DebugLogFormat is the log format for debug.
+	DebugLogFormat string
+
 	// FileAccess indicates how the filesystem is accessed.
 	FileAccess FileAccessType
 
@@ -214,6 +217,7 @@ func (c *Config) ToFlags() []string {
 		"--log=" + c.LogFilename,
 		"--log-format=" + c.LogFormat,
 		"--debug-log=" + c.DebugLog,
+		"--debug-log-format=" + c.DebugLogFormat,
 		"--file-access=" + c.FileAccess.String(),
 		"--overlay=" + strconv.FormatBool(c.Overlay),
 		"--network=" + c.Network.String(),

runsc/main.go

@@ -38,17 +38,18 @@ var (
 	// Docker, and thus should not be changed.
 	rootDir     = flag.String("root", "", "root directory for storage of container state")
 	logFilename = flag.String("log", "", "file path where internal debug information is written, default is stdout")
-	logFormat   = flag.String("log-format", "text", "log format: text (default) or json")
+	logFormat   = flag.String("log-format", "text", "log format: text (default), json, or json-k8s")
 	debug       = flag.Bool("debug", false, "enable debug logging")
 
 	// These flags are unique to runsc, and are used to configure parts of the
 	// system that are not covered by the runtime spec.
 
 	// Debugging flags.
-	debugLog   = flag.String("debug-log", "", "additional location for logs. If it ends with '/', log files are created inside the directory with default names. The following variables are available: %TIMESTAMP%, %COMMAND%.")
-	logPackets = flag.Bool("log-packets", false, "enable network packet logging")
-	logFD      = flag.Int("log-fd", -1, "file descriptor to log to.  If set, the 'log' flag is ignored.")
-	debugLogFD = flag.Int("debug-log-fd", -1, "file descriptor to write debug logs to.  If set, the 'debug-log-dir' flag is ignored.")
+	debugLog       = flag.String("debug-log", "", "additional location for logs. If it ends with '/', log files are created inside the directory with default names. The following variables are available: %TIMESTAMP%, %COMMAND%.")
+	logPackets     = flag.Bool("log-packets", false, "enable network packet logging")
+	logFD          = flag.Int("log-fd", -1, "file descriptor to log to.  If set, the 'log' flag is ignored.")
+	debugLogFD     = flag.Int("debug-log-fd", -1, "file descriptor to write debug logs to.  If set, the 'debug-log-dir' flag is ignored.")
+	debugLogFormat = flag.String("debug-log-format", "text", "log format: text (default), json, or json-k8s")
 
 	// Debugging flags: strace related
 	strace         = flag.Bool("strace", false, "enable strace")
@@ -133,6 +134,7 @@ func main() {
 		LogFilename:    *logFilename,
 		LogFormat:      *logFormat,
 		DebugLog:       *debugLog,
+		DebugLogFormat: *debugLogFormat,
 		FileAccess:     fsAccess,
 		Overlay:        *overlay,
 		Network:        netType,
@@ -166,15 +168,7 @@ func main() {
 		logFile = f
 	}
 
-	var e log.Emitter
-	switch *logFormat {
-	case "text":
-		e = log.GoogleEmitter{&log.Writer{Next: logFile}}
-	case "json":
-		e = log.JSONEmitter{log.Writer{Next: logFile}}
-	default:
-		cmd.Fatalf("invalid log format %q, must be 'json' or 'text'", *logFormat)
-	}
+	e := newEmitter(*logFormat, logFile)
 
 	subcommand := flag.CommandLine.Arg(0)
 	if *debugLogFD > -1 {
@@ -195,13 +189,13 @@ func main() {
 			cmd.Fatalf("error dup'ing fd %d to stderr: %v", f.Fd(), err)
 		}
 
-		e = log.MultiEmitter{e, log.GoogleEmitter{&log.Writer{Next: f}}}
+		e = log.MultiEmitter{e, newEmitter(*debugLogFormat, f)}
 	} else if *debugLog != "" {
 		f, err := specutils.DebugLogFile(*debugLog, subcommand)
 		if err != nil {
 			cmd.Fatalf("error opening debug log file in %q: %v", *debugLog, err)
 		}
-		e = log.MultiEmitter{e, log.GoogleEmitter{&log.Writer{Next: f}}}
+		e = log.MultiEmitter{e, newEmitter(*debugLogFormat, f)}
 	}
 
 	log.SetTarget(e)
@@ -236,6 +230,19 @@ func main() {
 	os.Exit(128)
 }
 
+func newEmitter(format string, logFile io.Writer) log.Emitter {
+	switch format {
+	case "text":
+		return &log.GoogleEmitter{&log.Writer{Next: logFile}}
+	case "json":
+		return &log.JSONEmitter{log.Writer{Next: logFile}}
+	case "json-k8s":
+		return &log.K8sJSONEmitter{log.Writer{Next: logFile}}
+	}
+	cmd.Fatalf("invalid log format %q, must be 'text', 'json', or 'json-k8s'", format)
+	panic("unreachable")
+}
+
 func init() {
 	// Set default root dir to something (hopefully) user-writeable.
 	*rootDir = "/var/run/runsc"